In various biological processes, there is a need to sense temperature and pressure associated with the processes. For example, in humans and other mammals it may be important to sense a body temperature as well as blood pressure. Other applications of temperature sensing include the detection of respiration, and respiration rate.
In one biological embodiment, the disclosed system and method may be used to sense temperature and pressure of a specimen (e.g., a mammal) in a physiological setting. Such sensing may be accomplished through non-invasive and/or invasive techniques. In those situations where direct exposure of the thermocouple junction is not possible, the junction may be encapsulated in a flexible, thermally-conductive covering so as not to impede the sensing of pressure and temperature variations it is intended to sense. It should be appreciated that a thermocouple formed with a generally-spherical, micro-bead type junction may be employed to sense not only changes in temperature, but also localized changes in pressure. In such embodiments, the reduced-size, bead-shaped thermocouple junction is preferably exposed to the physiological environment or specimen it is intended to sense in order to reliably provide a signal response to changes in temperature and/or pressure. As discussed herein, the response of the micro-bead thermocouple (e.g., a bead formed by welding of thin thermocouple wires, made from iron, and constantan or other known thermocouple combinations, is capable of sensing both temperature and pressure components.
For example, the sensor is contemplated as a pulse sensor, where the sampling frequency or resolution (response time of sensor and associated analog-to-digital interface) must be fast enough to permit accurate sensing of the analog output curve to represent physiological parameters such as a pulse. In such an embodiment, the response time and sampling rate of the sensor and associated electrical circuitry must be less than the maximum pulse rate to be sensed. At a minimum the sampling rate should be one half the maximum pulse rate to be sensed, but in order to assure higher accuracy, it is believed that sampling rates of one or more orders of magnitude greater than the maximum are preferred. Moreover, in order to use a thermocouple-based sensor, such systems may include a variable output threshold for sensing pulses.
In various industrial and man-made devices there is also a need to sense temperature and pressure associated with the process. And, aspects of the systems and methods disclosed herein are also applicable to such industrial processes. One such example is a molding process, wherein a part is molded using a material to fill a mold cavity. More specifically, the industrial process may include an injection or similar molding operation.
When the multi-variable sensor disclosed herein is to be employed in industrial processes such as material molding (e.g., injection molding), the sensor may be used to monitor and or control the industrial processes. In such embodiments, placement of the sensor, an exposed thermocouple bead, may be critical. Moreover, the location of the bead relative to the process (e.g., in the mold, in contact with melt material, in a vent, etc.) may be used to provide additional information on the process. Included in the following disclosure and figures are various examples and illustrations of the manner in which such sensors may be arranged and installed. Moreover, in the case of using the sensors in mold cavity vents, the sensors themselves may be laid out in an array of sensors and the output of the sensors used to control the molding process (e.g., control closing of a gate upon detection of cavity fill and pack). For example, the sensor leads may be placed in a vent slot in the mold, and held in place using a plug such that the sensor leads are placed into a “U” shapes and the sensor bead is exposed in the vent cavity to sense the air/gas being exhausted from the mold cavity. In a multi-cavity mold (e.g., 32 as illustrated in the following figures), an array of 32 vent sensors may be installed and monitored.
Disclosed in embodiments herein is a method for concurrently sensing a combined temperature and pressure of a process, comprising: sensing a plurality of cycles of the process using a micro-bead sensor in direct contact with an element of the process, including providing a sensor consisting of two dissimilar metal wires terminated by a generally-spherical, micro-bead junction suitable for exposure to the process; exposing the micro-bead junction to the process, where in the junction senses the process and produces a signal in response to the process; receiving the signal; converting the signal to data representing at least temperature and pressure using at least one reference point against which the sensor was calibrated; and at least temporarily, storing data representing the temperature and pressure in memory; wherein the sensing and receiving of the signal occurs at a rate less than one-half that of a period of the process cycle.
Also disclosed in embodiments herein is A system to measure at least temperature and pressure of a cyclic process, comprising: at least one generally spherical micro-bead sensor formed from dissimilar metals; electrical circuitry to receive a sensor output signal and convert the sensor output signal to a digital signal; a processor for receiving the digital signal and processing the received digital signal in order to quantify at least temperature and pressure components of the signal relative to at least one reference point against which the sensor was calibrated, the processor correcting for the reference point to produce an output representing at least two parameters.
The various embodiments described herein are not intended to limit the embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.